A trial lenses exchanged method, which is a subjective refraction tests, has been adopted for the prescription of glasses for selecting the most suitable lens for each user of glasses for some time. When the trial lenses exchanged method is conducted, a testee wears trial frames for trial lenses. Many kinds of trial lenses with various spherical diopters and astigmatic diopters and the like selected among a set of trial lenses are fitted in trial frames, thereby selecting the most suitable lens for each testee. A trial lens used in the trial lenses exchanged method has a grip portion on a periphery of a lens portion. By gripping the grip portion, the trial lens is set in and taken off from the trial frames.
A conventional trial lens is mainly made of glass. The trial lens is manufactured by attaching a holder ring member with a grip portion on the periphery of the lens cut (edge-filed) into the fixed size (Japanese Utility Model Laid-open No. Hei 4-22902). Some conventional trial lenses are plastic, but the manufacturing process after cutting is the same as that of glass trial lenses.
Besides manufacturing lenses, the conventional trial lens manufacture requires the process of manufacturing members for grip portions with different materials from the lenses and attaching the members on lenses, which takes a lot of time and labor.
Members for grip portions are made of metal in view of durability and easy operation, which causes the disadvantage that a trial lens is heavy as a whole. In complicated prescriptions for glasses for astigmatism, glasses for both far vision and near vision and the like, trial tests are conducted by setting more than one trial lenses one on another in trial frames so that the ears and nose of a testee get a heavy weight, which causes another disadvantage that the trial frames are easy to slip off. The diameter of the trial lens is small so that after-processing such as edge-filing and holder ring attaching is difficult. The grip portion is disposed at the fixed angle, for example, at the upper right or at the upper left of the lens in consideration of setting work in trial frames. In a trial lens with differences between the top and the bottom and between the right and the left, such as a progressive multifocal lens and a lens for an astigmatism, when a holder ring with a grip portion is attached on the periphery of the trial lens, precise positioning of the above fixed angle concerning the grip portion is required in accordance with an optical layout in the design of the lens about an optical center position and the like, which makes the attaching process of the holder ring difficult in a trial lens with a short diameter. Moreover, when the holder ring with the grip portion is caulked too strongly on the periphery of the lens, in a plastic lens, this situation causes an optical surface to be deformed, which brings about optical distortion and the like.
An object of the present invention is to provide a plastic trial lens, in which the process of manufacturing a member for a grip portion with different materials from a lens and attaching the member on the lens is omitted, the whole trial lens is more light-weight and the precise layout of the grip portion in relation to the lens portion is obtained, and an injection molded product to make the plastic trial lens, and moreover, a mold assembly to mold the injection molded product.